1. Field of The Invention
This invention relates to an engineering plastic composition with excellent flowability, heat stability, and desirable mechanical properties, and to articles made of the same.
2. Description of the Prior Art
Many resins are known-as engineering plastic materials. They include polyetherimide, polyarylketone, polysulfone, polyarylenesulfide, polyarylate, liquid crystal polyester, polyamide-imide, polycarbonate, polyphenyleneoxide, etc. These engineering plastic materials can be used in various kinds of articles that require a high-performance material with qualities such as excellent heat stability and mechanical properties. However, in general, the melt viscosities of engineering plastic materials are high, and as a result, the workability of the materials is poor. Therefore, it is not easy to use these engineering plastic materials for products to be formed with accuracy. For these reasons, there is a need for an engineering plastic composition that has a low melt viscosity, that is, satisfactory flowability, during molding.
In general, as methods by which the melt viscosity of polymers can be lowered, the following two methods have been adopted: (1) to decrease the molecular weight of the polymer, and (2) to add a plasticizer or to add a processing aid.
When the first method is used, the tensile strength, the impact strength, and other mechanical properties of the articles that are made of the polymer are worsened, and the heat stability of the articles declines. In the second method, many of the substances that can provide engineering plastic materials with plasticity have poor heat stability, so that these substances are not stable at the molding temperature for the engineering plastic materials. For these reasons, a plasticizer or processing aid that is effective with engineering plastic materials has not yet been found.
Many attempts have been made to improve the moldability or workability of engineering plastic materials. The conventional methods for the improvement of the engineering plastic materials listed above will be described below in detail.